These caves have yielded abundant, well-preserved evidence of ancient occupation by humans and have been designated a Unesco World Heritage Site.

The new remains were unearthed at the archaeological site of Sima del Elefante, which lies just a few hundred metres from two other locations which have yielded remains of early Europeans.

"It is the oldest human fossil yet found in Western Europe," said co-author Jose Maria Bermudez de Castro, director of Spain's National Research Centre on Human Evolution (CENIEH) in Burgos.

Ancient migration

Dr Bermudez de Castro told BBC News that the latest find had anatomical features linking it to earlier hominins (modern humans, their ancestors and relatives since divergence from apes) discovered in Dmanisi, Georgia - at the gates of Europe.

Several teeth were preserved with the jaw

The Georgian hominins lived some 1.7 million years ago and represent an early expansion of humans outside Africa.

The researchers therefore suggest that Western Europe was settled by a population of hominins coming from the east.

Once these early people had "won the West" they evolved into a distinct species - Homo antecessor, or "Pioneer Man", say the scientists.

The scientists now plan to investigate whether Pioneer Man might have been ancestral to Neanderthals and to even our own species Homo sapiens.

"In terms of European prehistory, this [find] is very significant," said Professor Chris Stringer, research leader in human origins at London's Natural History Museum.

The timing of the earliest human habitation in Europe has been controversial.

"The earliest hominins outside Africa are those from Dmanisi in Georgia. After that, we have occupations in Europe, but the ages are not very precise. They are also without hominin [remains]," said Dr Marina Mosquera, a co-author from the Rovira i Virgili University in Tarragona, Spain.

Reliable date

The Spanish researchers used three different techniques to date the new fossils: palaeomagnetism, cosmogenic nuclide dating and biostratigraphy.

The researchers said the new find represented the earliest reliably dated evidence of human occupation in Europe.

"What we have are the European descendents of the first migration out of Africa," said Dr Mosquera.

Professor Stringer said that until more material was discovered from Atapuerca, he was cautious about assigning the new specimen to the species Homo antecessor.

But he added: "However the specimen is classified, when combined with the emerging archaeological evidence, it suggests that southern Europe began to be colonised from western Asia not long after humans had emerged from Africa - something which many of us would have doubted even five years ago."

"It gives us confidence that Europe was not left out of the picture of the spread of early humans. Early humans got to Java and China by 1.5 million years ago and certainly some of the animal remains found at those Asian sites are found in Western Europe too."

He explained that the people at Sima del Elefante had made primitive stone tools and would have had relatively small brains. The outside of the jawbone had some primitive anatomical features, but the inside displayed some more advanced characteristics, he added.

This suggested they may have been evolving towards humans which are known from much later in time, such as Homo heidelbergensis.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.